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Acidulated phosphate fluoride (APF), Duraphat or Fluor Protector, was applied to the molar teeth of rats fed a cariogenic diet. The first maxillary molar teeth were subjected to a microbiopsy procedure for fluoride analysis and the mandibular molars scored for caries. All three topical fluoride agents produced a significant increase in the fluoride content of the outermost 5.0 micron of enamel. Only APF produced a significant reduction in caries incidence at all sites.

The chemical treatment of tooth surfaces to improve bonding of dental materials to enamel and dentin is one of the approaches in overcoming the lack of adhesion of the available restorative materials to tooth structure. The acid etch technique is now an accepted procedure in restorative and preventive dentistry and for the direct bonding of orthodontic attachments. The pulpal response elicited by one of the conditioning agents, 50 % H3PO4 applied for 1 minute, was investigated in the teeth of the vervet monkey. The differences between most of the criteria used to evaluate the pulpal responses in acid-treated and control teeth at three time intervals, namely 4, 14 and 42 days, were statistically significant. These results suggest that a protective lining should be used to cover exposed dentin before etching adjacent enamel surfaces with 50 % H3PO4.

The DMFT Index, degree of fluorosis (DEGF), and enamel fluoride concentration (F) were determined in 88 children living in a high- and 79 children living in a low-fluoride area in South Africa. The following interrelationships between these parameters were found: in both areas there was a significant negative correlation between log F and age; in the high-fluoride area there was a significant positive correlation between log F and DEGF; and in the combined data from the two areas there were significant correlations between log F and area, log F and age, and log F and DEGF, and a significant association between DEGF and area. There were no significant correlations between DMFT and log F and between DMFT and DEGF.

In a previous study enamel fluoride uptake from fluoride-containing orthodontic cements was evaluated after a 21-day period. The enamel fluoride uptake from a zinc phosphate cement (A), a zinc phosphate cement containing 5 per cent stannous fluoride by weight (B), and a silicophosphate cement (C) was compared. The results indicated that there was a net loss of fluoride from enamel beneath the orthodontic bands cemented with A while the enamel beneath B and C acquired significant amounts of fluoride. The purpose of the present study was to evaluate enamel fluoride uptake after 12 weeks and the effect of the fluoride uptake or loss by the enamel on acid resistance. Five teeth each had bands cemented with cements A, B, and C, respectively, and were individually suspended in synthetic saliva for 12 weeks at 37 ° C. Following this period the bands were removed, the cements were carefully cleaned off the teeth, and the crowns of the teeth were individually suspended in a lactic acid buffer at pH 4 for 4 weeks. Each tooth crown was then sectioned longitudinally and examined microradiographically to study the degree of enamel demineralization. Characteristic subsurface enamel carieslike lesions were noted on all the specimens studied. The carieslike lesions in the enamel exposed to the fluoride-containing cements were considerably reduced. The enamel which had acquired fluoride from the fluoride-containing cements was apparently more resistant to artificial caries attack.

Summary None of the materials presently available to the dental profession truly dhere to enamel and dentine. Conditioning of the enamel surface with phosphoric acid greatly increases the bonding of dental materials to tooth structure and the etching technique is now an accepted and widely applied procedure in dentistry. During the development and laboratory evaluation of new dental materials, the resin-enamel bond strength is determined by means of tensile loading tests. The site of failure is often recorded as occurring within the test material; partly within the material; at the adhesive-enamel interface; within the enamel; or in a combination of these sites. An epoxy resin formulation developed for the direct bonding of orthodontic attachments was used as the adhesive and enamel etched with 50% phosphoric acid as the adherend surface. Experimental bonds were subjected to tensile stresses to failure and both the enamel and adhesive aspects of the fractured bonds examined by scanning electron microscopy. The results indicate that the sites of failure cannot be reliably classified by visual examination per se or under low magnification. A model is proposed to elucidate the characteristics of interfacial failures. This experimental model was tested by surface roughness profiles and atomic absorption spectrometry.

Seventy-five extracted human permanent molars were embedded in brass cups with cold-cure acrylic. Immediately prior to the preparation of a test specimen, the occlusal surface was ground wet on 180 followed by 600 grit SiC to expose dentin. The Scotchprep Dentin Primer was applied to the dried dentin surface with a brush for 60 seconds, and dried with compressed air for 15 seconds. The tooth was mounted in a special device containing a split Teflon mold with a circular hole, 3.5 mm in diameter and 5 mm deep, and A:0.5 microL (50 microns), B:1.0 microL (100 microns), C:2.5 microL (250 microns), D:5 microL (500 microns) or E:10 microL (1000 microns) Scotchbond 2 pipetted into the teflon mold. The adhesive was cured by visible light for 30 seconds. Three increments of Silux were transferred to the Teflon mold, compressed firmly, and each cured for 30 seconds. The test specimens were disassembled 15 minutes after cure and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied via a knife-edge rod in an Instron machine. The shear bond strength was expressed in MPa. The data were analyzed by ANOVA and Duncan's multiple range test. The mean (+/- SD) of the shear bond strengths were: A: 8.8 (3.5), B: 7.9 (2.7), C: 6.8 (2.5), D: 8.1 (4.2), E: 5.3 (2.4). Adhesive thickness from 50 microns to 500 microns (A, B, C and D) had no significantly different effect on shear bond strength. An adhesive thickness of 1000 microns resulted in a significant reduction in shear bond strength.

The purpose of this in vitro study was to determine the effects of phosphoric acid (H3PO4) concentration and duration of etching on the shear bond strength of an orthodontic bonding resin to enamel. Nine bonding procedures, each involving 18 extracted human maxillary permanent canines, were used. Ground enamel surfaces were etched with a 37% H3PO4 solution, a 15% H3PO4 gel, or a 5% H3PO4 solution for 60, 30, and 15 seconds, respectively. Cylinders of an orthodontic bonding resin, Concise, were prepared in a special device. The test specimens were disassembled 15 minutes after preparation and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied to the bonded cylinders at a crosshead speed of 0.02 in.min-1 in an Instron testing machine, and the shear bond strengths were calculated and expressed in MN.m-2. A two-factor analysis of the data showed that the H3PO4 concentration had no significant effect on the shear bond strength, but the duration of etching affected shear bond strength significantly. The enamel aspects of the fractured test specimens were examined microscopically and the percent failure within the bonding resin at the bonding sites estimated. The correlation between shear bond strength and percentage failure within the bonding resin was not significant. The effects of the nine etching procedures on ground and unground enamel surfaces were studied by scanning electron microscopy. The etching procedures produced well-defined etching patterns on both ground and unground enamel surfaces.

The objective was to determine the effect of storage media and the duration of storage of extracted teeth on the shear bond strength (SBS) of Scotchbond 2/Silux to dentin. Extracted human mandibular and maxillary first permanent molars were stored in buffered formalin (A), 1% chloramine (B), 70% ethanol (C), physiological saline (D), or 0.05% thymol (E). Fifteen test specimens were prepared on teeth stored in each medium two days after extraction (Procedures A1 to E1) or after six months storage (Procedures A2 to E2). The teeth were embedded in brass tooth cups and the occlusal surfaces ground wet on 180 and then 600 grit SiC immediately prior to the preparation of a test specimen. The Scotchprep Primer and the Scotchbond 2 Adhesive were applied to the dentin surfaces as directed by the manufacturer. Cylinders of Silux Composite were bonded to the treated dentin surfaces in a special device. The specimens were removed 15 minutes after cure and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied to the bonded cylinders in an Instron machine at a crosshead speed of 0.02 inch.min-1. The SBS were calculated and expressed in MN.m-2. The data were analyzed by ANOVA and Duncan's multiple range test at the 5% level of significance.2+e mean SBS + SD

The caries inhibitory effect of optimally fluoridated drinking water is well documented. Communities are often exposed to naturally fluoridated water with F content exceeding the optimal level. The purpose of this study was to determine the relationship between enamel fluoride, degree of fluorosis (DEGF) and caries incidence (DMFT) in an endemic fluoride area. Eighty-five 14- to 16-year-old children (37 males and 48 females) who were born and had been living continually in the town of Kenhardt in South Africa were selected for this study. The fluoride content of the common water supply is 3.2 ppm F. The DMFT and DEGF were determined clinically. Acid etch biopsies were carried out on both maxillary central incisors of each subject. Ca and F analysis were carried out and mass enamel expressed in microgram and mass F in pg. Data transformations to loge mass F (1nF), loge mass En (1nEn) and square root DMFT were made. The 1nF values were corrected to a standardized depth of 10 micrometer (208.6 microgram enamel equivalent mass) by covariance analysis. Correlations between the parameters square root DMFT, 1nF ad DEGF were calculated, adjusting for the sex of the individual. The correlations were as follows: (formula: see text). A positive association among the three parameters was established.

In this investigation heat-sealed gutta-percha (A) reinforced with Adaptic (B), ASPA (C), Cupralloy without (D) and with (E) varnish, Spheraloy without (F) and with (G) varnish were used as retrofilling materials. Seventy maxillary central incisors with Class I canal anatomy were selected. Marginal leakage at the apical filling/root canal interface was evaluated quantitatively by means of a fluorescent dye technique. All statistical tests were computed at the 5 percent level of significance. Analysis of variance revealed that differences in microleakage among retrofillings were significant. Tukey's test of multiple contrasts was used to isolate statistically significant differences between all pairs of means. The following results were obtained: D F A G E C B Retrofillings are ranked in descending order of microleakage. Means that are linked were not significantly different.

Summary Low viscosity bonding resins have been introduced for use on etched enamel surfaces prior to the application of the viscous composite resins. In this in vitro study the effects of a low viscosity bonding resin on the bond strength, adaptation and microleakage of a composite resin to etched enamel were evaluated. The low viscosity bonding resin did not improve the tensile bond strength of a composite resin to etched enamel, did not increase resin penetration into etched enamel and did not decrease marginal leakage at the composite resin/etched enamel interface. The continued use of low viscosity bonding resins in clinical dentistry is questioned.

The physical and chemical properties of restorative materials and procedures that influence the extent of microleakage at the tooth/restoration interface are discussed. Adhesion to enamel is achieved and microleakage at the enamel/restoration interface has been controlled by acid etching enamel surfaces with orthophosphoric acid. The acid concentration and the duration of etching are reviewed. Adhesion to dentin and microleakage at the restoration/dentin (cementum) interface are more difficult. The development of dentin bonding agents and the tremendous advances made with these restorative systems are reviewed. Particular attention is directed towards the Gluma/Lumifor dentin bonding restorative system and the development of an experimental conditioning solution for both enamel and dentin.

The results of this study indicated that heat-sealed gutta-percha alone and when reinforced with Adaptic or a glass ionomer cement provided the most effective apical seal. It is therefore proposed to expand this study to include these materials and zinc-free Spheraloy and Cupralloy amalgams as retrofilling materials. The amalgams will be used with and without cavity varnish.

Conditioning with 50% phosphoric acid produces preferential etching of the enamel surface. Intimate interfacial contact is established between the adhesive and the etched enamel and tags of resin up to 50 μm in length project into the conditioned enamel surface. Etching increases the wettability of the enamel surface.

Sectioning of the inferior alveolar nerve in rats maintains the patency of the mandibular canal. If the inferior alveolar neurovascular bundle is avulsed, however, the mandibular canal becomes obliterated by bone within a short time. The connective tissue component of the degenerated nerve maintains the patency of the canal.